drm/amd/display: Round calculated vtotal

[WHY]
The calculated vtotal may has 1 line deviation. To get precisely
vtotal number, round the vtotal result.

Cc: Mario Limonciello <[e-mail]>
Cc: Alex Deucher <[e-mail]>
Cc: [e-mail]
Reviewed-by: Anthony Koo <[e-mail]>
Signed-off-by: Robin Chen <[e-mail]>
Signed-off-by: Alex Hung <[e-mail]>
Tested-by: Daniel Wheeler <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/display/modules/freesync/freesync.c

···
 
 	v_total = div64_u64(div64_u64(((unsigned long long)(
 			frame_duration_in_ns) * (stream->timing.pix_clk_100hz / 10)),
-			stream->timing.h_total), 1000000);
+			stream->timing.h_total) + 500000, 1000000);
 
 	/* v_total cannot be less than nominal */
 	if (v_total < stream->timing.v_total) {